A CMOS image sensor includes a plurality of pixels each having a photoelectric conversion element for converting an incident light into an electric signal, and an MOS transistor for reading the electric signal from each pixel. The CMOS sensor has advantages of low voltage and low power consumption, and thus a use range thereof is widened to a camera for a cell phone, a digital still camera, a digital video camera, or the like.
The CMOS image sensor includes a photodiode formed in a substrate as a photoelectric conversion element, a dielectric layer with a plurality of wiring layers formed thereon, and a color filter and a micro lens which are formed on the dielectric layer. In this instance, the color filter has a red color filter, a green color filter, and a blue color filter, which are formed for every pixel and are formed vertically to correspond to each photodiode. Therefore, for example, red light passes through the red color filter, and the photodiode below the red color filter generates and stores an electric charge in accordance with a quantity of light. Further, the electric charge generated by the photodiode flows in a floating diffusion region through a transfer transistor in which an electric signal is stored.
However, as the image sensor is reduced in size while the number of pixels is increased, the pixel is reduced in size. The reduction in size of the pixel causes an interval between the wiring layers to be shortened. If the interval between the wiring layers is shortened, there is a crosstalk phenomenon in which the light supplied from the color filter to the photodiode collides against the wiring layers and thus is scattered. Occurrence of the crosstalk phenomenon leads to reduction in quantity of the light supplied to the photodiode. Accordingly, the amount of the electric charges generated by the photodiode is also decreased. As a result, there is a problem in that the sensitivity of the image sensor is decreased, and a color intensity characteristic is deteriorated.